optimummaximum Posted June 27, 2009 Report Share Posted June 27, 2009 My 2003 deville has developed a rough idle. When cold it seems to run fine. after it has reached operating temperature it idles rough. Seems to have a miss. I have recently put new ac delco spark plugs, checked for vacumm leaks, plenum gasket is in order, cleaned the throttle body and replaced the crankshaft position sensors. I replaced the cps's because the car stalled as described by other posts and I thought it may be part of the rough idle issue but it still has the problem. Car has 150k. It is used in a sedan service and is maintained well. The only codes that are recurring are c1287 and c1288. I believe these refer to the steering position sensor. I am uncertain of any relationship to the rough idle. I was thinking the o2 sensors but they seem to be working as they should. I am using a scantool and the voltage and short term fuel trim for all three sensors seem to be doing what they are meant to do. thanks in advance for your help. Link to comment Share on other sites More sharing options...
BodybyFisher Posted June 27, 2009 Report Share Posted June 27, 2009 I use a diagnostic tool called Autotap, with it you could determine real time misfires, do you have the ability to do that? The reason I say this, is that you could locate the mis and focus on that cylinder. I would pull each coil pack and check the plug connections for corrosion and a good positive connection at each plug. Logan has a famous statement that he makes, he keeps a coil pack in his trunk... Check your coil packs if the connections are OK Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
optimummaximum Posted June 27, 2009 Author Report Share Posted June 27, 2009 I use a diagnostic tool called Autotap, with it you could determine real time misfires, do you have the ability to do that? The reason I say this, is that you could locate the mis and focus on that cylinder. I would pull each coil pack and check the plug connections for corrosion and a good positive connection at each plug. Logan has a famous statement that he makes, he keeps a coil pack in his trunk... Check your coil packs if the connections are OK I use a a program called digimoto. It is a USB connection to my laptop. I am not sure it can focus on a specific cyl for misfire. It does show misfire test as a constant monitor. But I am assuming it is just reading data from the vehicle and it would only show as a p30? code. I did have a history code of misfire on cyl 1 but I am not certain how old it was and it has not returned. I will check the coil packs. I also recleaned the tb and changed the air filter. the fuel filter was recently changed. It seems to be running better. I will have to drive it for a day or so to see if the problem is gone. preliminary drive seems optimistic. I also read about cleaning the EGR valve. could that be a potential culprit? Is there a relearn process or special procedure to perform after changing the crankshaft position sensor? Link to comment Share on other sites More sharing options...
BodybyFisher Posted June 27, 2009 Report Share Posted June 27, 2009 I use a diagnostic tool called Autotap, with it you could determine real time misfires, do you have the ability to do that? The reason I say this, is that you could locate the mis and focus on that cylinder. I would pull each coil pack and check the plug connections for corrosion and a good positive connection at each plug. Logan has a famous statement that he makes, he keeps a coil pack in his trunk... Check your coil packs if the connections are OK I use a a program called digimoto. It is a USB connection to my laptop. I am not sure it can focus on a specific cyl for misfire. It does show misfire test as a constant monitor. But I am assuming it is just reading data from the vehicle and it would only show as a p30? code. I did have a history code of misfire on cyl 1 but I am not certain how old it was and it has not returned. I will check the coil packs. I also recleaned the tb and changed the air filter. the fuel filter was recently changed. It seems to be running better. I will have to drive it for a day or so to see if the problem is gone. preliminary drive seems optimistic. I also read about cleaning the EGR valve. could that be a potential culprit? Is there a relearn process or special procedure to perform after changing the crankshaft position sensor? Thats cool, I use Autotap and it also connects to my laptop via a USB port. I can call up the misfire history and current misfires by cylinder. Check your #1 coil connections, and possibly swap in a known good coil pack Have you disconnected the battery after installing the crank sensor?, disconnect the battery and let the system go through a relearn You would get an EGR pindle position code if it was EGR related and it would idle very poorly Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
Ranger Posted June 27, 2009 Report Share Posted June 27, 2009 Did you or did you not find a vacuum leak in the plenum? Link to comment Share on other sites More sharing options...
optimummaximum Posted June 28, 2009 Author Report Share Posted June 28, 2009 Did you or did you not find a vacuum leak in the plenum? No leak in the plenum... I will disconnect the battery... I will check the coil pack.... Link to comment Share on other sites More sharing options...
optimummaximum Posted July 2, 2009 Author Report Share Posted July 2, 2009 I finally got an error... misfire on cyl 5. It was initially p0300 and then changed into p0305. I pulled the coil pack and the posts were corroded. I cleaned them and reinstalled the pack. . Still missing. I guess it is time for a coil cassette. Is there anything else I should do before I purchase. Also, I am getting p0410 secondary air... My pump is working... Is there a way to test the check valves to see if they are working? Link to comment Share on other sites More sharing options...
BodybyFisher Posted July 2, 2009 Report Share Posted July 2, 2009 It sounds like you have done a lot already, if there is anyway for you to swap in a known good coil pack, I would do that, any scrap yards near you? Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
optimummaximum Posted July 5, 2009 Author Report Share Posted July 5, 2009 Thanks for all your help... As was suggested the problem was the coil pack. Cleaning the posts did not help. For your info.... Some prices. Dealer $335.000 Rockauto.com $290.00 plus shipping Local parts store $400.00 (Some items are priced better must not be a regular part for them AUTO ZONE $200.00 Duralast -- Delphi Link to comment Share on other sites More sharing options...
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